Question

In-vitro template-independent RNA synthesis is a feature of
(a)RNA polymerase
(b)Reverse transcriptase
(c)Ochoa enzyme
(d)DNA polymerase

Answer 1

Hint: This was discovered by Severo Ochoa. It is basically a polynucleotide polymerase and is used for the catalysis of RNA polymerization reactions majorly, it helps the polymerization in a template-independent manner.

Complete answer:
The RNA polymerase is an enzyme that can synthesize the RNA in-vitro but it needs DNA template synthesis. Polynucleotide phosphorylase on the other hand is an enzyme that is also called an Ochoa enzyme that can synthesize template-independent RNA in-vitro. This enzyme basically uses ribonucleoside diphosphates instead of ribonucleoside triphosphates used by RNA polymerase. Additionally, RNA polymerase needs a DNA template whereas Reverse transcriptase synthesizes DNA from the RNA template, and DNA polymerase makes DNA from a DNA template. But, the Ochoa enzyme can make template-independent RNA in-vitro.

Additional information:
PNPase is the short form for Polynucleotide Phosphorylase that is also known as the Ochoa enzyme. This enzyme has two functions. That means that it dismantles the RNA chain starting at the 3’ end and working toward the 5’ end and is also actively involved in mRNA processing and degradation in bacteria, plants, and humans.
This enzyme was discovered by Marianne Grunberg-Manago, who worked in Severo Ochoa’s lab in 1955. Initially, the PNPase RNA polymerization activity was believed to be responsible for DNA-dependent synthesis mRNA, but the notion got disproved by the late 1950s.
So, the correct answer is option (C) ‘Ochoa enzyme’.

Note: The same abbreviation (PNPase) that is used for the Ochoa enzyme is also used for another enzyme, Purine nucleoside phosphorylase, which is involved in purine metabolism and is unrelated to the above process.